Helquat Dyes - ACS Publications - American Chemical Society

Subscriber access provided by ORTA DOGU TEKNIK UNIVERSITESI KUTUPHANESI

Article

Helquat Dyes: Helicene-Like Push-Pull Systems with Large Second-Order Nonlinear Optical Responses Benjamin John Coe, Daniela Rusanova , Vishwas D. Joshi, Sergio Sánchez, Jan Vavra, Dushant Khobragade, Lukas Severa, Ivana Cisarova, David Saman, Radek Pohl, Koen Clays, Griet Depotter, Bruce S. Brunschwig, and Filip Teply J. Org. Chem., Just Accepted Manuscript • DOI: 10.1021/acs.joc.5b02692 • Publication Date (Web): 04 Feb 2016 Downloaded from http://pubs.acs.org on February 5, 2016

Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a free service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are accessible to all readers and citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.

The Journal of Organic Chemistry is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.

Page 1 of 30

The Journal of Organic Chemistry

1 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Helquat Dyes: Helicene-Like Push-Pull Systems with Large Second-Order Nonlinear Optical Responses Benjamin J. Coe,*,† Daniela Rusanova,† Vishwas D. Joshi,‡ Sergio Sánchez,† Jan Vávra,‡ Dushant Khobragade,‡ Lukáš Severa,‡ Ivana Císařová,§ David Šaman,‡ Radek ⊥

Pohl,‡ Koen Clays, Griet Depotter, Bruce S. Brunschwig, and Filip Teplý*,‡

†

School of Chemistry, University of Manchester, Oxford Road, Manchester M13 9PL, U.K.

‡

Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech

Republic, v.v.i., Flemingovo n. 2, 166 10 Prague 6, Czech Republic §

Department of Inorganic Chemistry, Charles University, Hlavova 2030/8, 128 43 Prague 2,

Czech Republic

⊥

Department of Chemistry, University of Leuven, Celestijnenlaan 200 D, B-3001, Belgium Molecular Materials Research Center, Beckman Institute, MC 139-74, California Institute

of Technology, 1200 East California Boulevard, Pasadena, California 91125, United States

ACS Paragon Plus Environment


Page 2 of 30

2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

ABSTRACT: Helquat dyes combine a cationic hemicyanine with a helicene-like motif, a new blueprint for chiral systems with large and tunable nonlinear optical (NLO) properties. We report a series of such species, with characterization including determination of static first hyperpolarizabilities β0 via hyper-Rayleigh scattering and Stark spectroscopy. The measured

β0 values are similar to or substantially larger than that of the commercial chromophore E-4′(dimethylamino)-N-methyl-4-stilbazolium. Density functional theory (DFT) and timedependent DFT calculations on two of the new cations are used to probe their molecular electronic structures and optical properties. Related molecules are expected to show bulk second-order NLO effects in even nonpolar media, overcoming a key challenge in developing useful materials.


Page 3 of 30


3 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Introduction Manipulating light via molecular nonlinear optical (NLO) effects1 is useful in areas like THz wave generation for bioanalysis, security scanning and space communication.2 Pyridinium salts like DAST (E-4′-(dimethylamino)-N-methyl-4-stilbazolium tosylate, Scheme 1a)3,4 are among the best organic NLO materials. Normally, a polar bulk structure is required if the molecular first hyperpolarizability β is to lead to a nonzero value of the second-order NLO susceptibility χ(2). Second harmonic generation (SHG) is the most immediately useful and widely studied second-order NLO effect.

Scheme 1. (a) DAST; (b) a diquat NLO chromophore; (c) a helquat dye introduced here

Recently, new diquat chromophores were introduced (Scheme 1b),5 with nonresonant

β responses (β0) larger than that of the DAS+ cation. Furthermore, a [6]helicene bisquinone derivative shows very large SHG in Langmuir-Blodgett films.6 However, the structural motifs of cationic styryl dyes and helicenes have never been combined for NLO purposes. Indeed, azahelicenium dyes7 are largely overlooked, except in reports from the groups of Lacour8 and Arai.9 Their NLO properties have not been reported. Importantly, a helical conjugated molecule has a high nondipolar β tensor component βxyz; this can give a large χ(2) in even a nonpolar material, circumventing a key challenge in creating useful substances. Recently, we reported the prominent chiroptical properties of helquat dyes.10a Here, we describe new chromophores of this type (Scheme 1c), and use hyper-Rayleigh scattering (HRS), Stark spectroscopy and density functional theory (DFT) to assess their second-order NLO responses.



Page 4 of 30

4 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Results and Discussion

Scheme 2. Synthesis of (a) [5]helquat dyes 1–5, and (b) [6]helquat dyes 6–10 via Knoevenagel condensation chemistry

Figure 1. Representations of the molecular structures of (a) the PF6– analogue of salt 1 and (b) 6•H2O (50% probability ellipsoids). H = white; C = grey; N = blue; P = orange; F = green; O = red; S = gold

1–10 are prepared via Knoevenagel condensations from methyl-substituted [5]helquat or [6]helquat (Scheme 2a and 2b, respectively). The products are characterised by 1H/13C NMR spectroscopy, elemental analyses and +electrospray mass spectrometry. Also, two single-crystal X-ray structures have been obtained (Figure 1 and Supporting Information). Although the PF6– analogue of 1 and the triflate salt 6 adopt centrosymmetric structures, this does not preclude significant χ(2), if βxyz components are substantial. Also, anion metathesis can modify readily crystal packing arrangements.10e The UV–vis spectra of 1–10 show an intense low energy absorption band, attributable to intramolecular charge-transfer (ICT) from the amino unit to the helquat fragment. This behaviour is confirmed by DFT and time-dependent DFT (TD-DFT) calculations on the cations in salts 1 and 6 (denoted 1′′ and 6′′, respectively; details in Supporting Information).


Page 5 of 30


5 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

However, the theoretical λmax values are blue-shifted significantly when compared with those measured (Figure 2).

Figure 2. CAM-B3LYP/6-311G(d)-calculated (blue) and experimental (green) UV–vis absorption spectra of 1′′ and 6′′ in MeCN. The ε-axes refer to the experimental data only (for the OTf– salts) and the vertical axes of the calculated data are scaled to match the main experimental absorptions. The fos-axes refer to the individual calculated transitions (red) The MOs are determined from gas phase calculations, while the TD-DFT calculations are carried out by using a conductor-like polarizable continuum model (CPCM) of MeCN. Depictions of the frontier MOs and computed transitions are included in the Supporting Information (Figures S2 and S3, Table S1). For 1′′, the lowest energy transition has mainly HOMO → LUMO character with a small HOMO → LUMO+1 contribution. On the other hand, this transition in 6′′ has similar contributions from HOMO → LUMO and HOMO → LUMO+1. In both cations, the HOMO is located on the 4-(dimethylamino)styryl fragment, while the LUMO is based mostly on the helquat unit, and the LUMO+1 is spread over the whole molecule (Figure 3).



Page 6 of 30

6 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 3. CAM-B3LYP/6-311G(d)-derived contour surface diagrams (gas phase) of the MOs involved in the low energy transitions for cations 1′′ (472 nm) and 6′′ (449 nm) in a CPCM of MeCN (isosurface value 0.03 au)

The results of 800 nm fs HRS measurements11 of resonant β values and β0 (derived by using the two-state model)12 for 1–10 in MeCN are shown in Table 1, together with data reported for [DAS]PF6.13 The DFT and TD-DFT results confirm that the new chromophores are described adequately as two-state systems, i.e. a single low energy electronic transition is expected to dominate the NLO response.


Page 7 of 30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48


7 Table 1. ICT absorption, Stark spectroscopic and HRS data for the salts 1–10 Salt 1 2 3 4 5 6 7 8 9 10 [DAS]PF6i

λmaxa

λmaxb

Εmaxb

(nm)

(nm)

(eV)

520 570 513 539 600 496 538 485 516 564 470

526 569 524 549 588 498 537 493 533 564 480

2.36 2.18 2.37 2.26 2.11 2.49 2.31 2.52 2.33 2.20 2.58

fosb,c 0.68 0.61 0.66 0.96 0.66 0.56 0.71 0.46 0.82 0.78 0.80

µ12b,d

β0[S]f

β800g

β0[H]h

(D)

∆µ12b,e (D)

(10–30 esu)

(10–30 esu)

(10–30 esu)

8.7 8.6 8.6 10.6 9.1 7.8 9.0 7.0 9.7 9.7 9.1

14.3 24.2 20.6 25.6 25.9 22.5 20.2 29.5 21.1 26.1 16.3

258 442 340 658 566 252 364 260 424 588 236

184 ± 15 196 ± 7 235 ± 26 302 ± 32 275 ± 26 171 ± 12 209 ± 6 302 ± 13 401 ± 43 376 ± 32 440 ± 30

73 ± 6 99 ± 4 89 ± 10 135 ± 14 150 ± 14 57 ± 4 93 ± 3 90 ± 4 156 ± 17 187 ± 16 110 ± 7

In MeCN at 295 K. b In PrCN at 77 K. c Obtained from (4.32 × 10–9 M cm2)εmax × fw1/2 where εmax is the maximal molar extinction coefficient and fw1/2 is the full width at half height (in wavenumbers). d Calculated from eq. 1. e Calculated from fint∆µ12 by using fint = 1.33. f Calculated from eq. 2. The quoted cgs units (esu) can be converted into SI units (C3 m3 J–2) by dividing by 2.693 × 1020, or into atomic units by dividing by 0.8640 × 10–32. g Obtained from HRS measurements with a 800 nm Ti3+:sapphire laser and MeCN solutions at 295 K. h Derived from β800 by application of the two-state model.12 i Data taken from ref. 13.

a



Page 8 of 30

8 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Within the [5]helquat series 1–5, β0[H] increases in the order 1 ≤ 3 ≤ 2 < 4 ≤ 5. As for related pseudolinear pyridinium compounds,14 the stronger π-electron donating ability of the julolidinyl group vs 4-(dimethylamino)phenyl that is evident in the ICT energies Emax translates into larger apparent β0[H] responses for 2 vs 1 and for 5 vs 4. However, the difference for the latter pair is within the experimental error limits. Also as expected, extending the π-conjugation on moving from 1 to 4 or from 2 to 5 increases β0[H] significantly. The Emax values for 3 and 4 indicate that the electron-donating strength of the aminoaryl unit is weakened when one of the vinyl groups is incorporated into a phenyl ring, and β0[H] thus decreases. The data for the [6]helquats 6–10 show the same overall trends, with β0[H] increasing in the order 6 < 8 ≤ 7 < 9 ≤ 10. Replacing a [5]helquat with a [6]helquat while also changing the position of attachment of the donor substituent with respect to the quaternised N atom always causes the ICT band to blue shift by ca. 0.1 eV. However, the observed variations in β0[H] show no clear trend and are in several cases insignificant. The results of Stark spectroscopic studies15 on the ICT bands of the salts 1–10 in PrCN at 77 K are shown in Table 1, together with data for [DAS]PF6.13 Representative spectra for 2, 5, 7 and 10 are shown in Figure 4. In contrast to the HRS technique that is complicated by resonance effects, the Stark-based approach allows indirect estimation of β0 values. For all except 5, the ICT bands of 1–10 show small red shifts or no significant change on moving from MeCN solutions to PrCN glasses, and the energy ordering within the two series remains constant (Table 1). The decreases in Emax on extending a vinyl to 1,3butadienyl bridge or replacing a 4-(dimethylamino)phenyl with julolidinyl group are maintained at 77 K. The µ12 values determined by using eq. 1 all fall in a relatively narrow range, with small increases on conjugation extension. In general, ∆µ12 also increases in the same manner and as expected, although the value for 2 is unexpectedly large, while that for 9 is low.


Page 9 of 30


9 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Figure 4. Spectra and calculated fits for the salts 2, 5, 7 and 10. Top panel: UV–vis absorption spectrum; middle panel: electroabsorption spectrum, experimental (blue) and fits (green) according to the Liptay equation;15d bottom panel: contribution of 0th (blue), 1st (green) and 2nd (red) derivatives of the absorption spectrum to the calculated fits

For the [5]helquats 1–5, the β0[S] values determined by using eq. 2 increase in the order 1 ≤ 3 ≤ 2 ≤ 5 ≤ 4, almost paralleling the β0[H] data (see above). For the [6]helquats 6– 10, the β0[S] ordering of 6 ≤ 8 ≤ 7 ≤ 9 ≤ 10 matches the HRS trend exactly. The expected increases in the NLO response on enhancing the electron donor strength or extending the conjugation are thus also shown by most of the Stark-derived data, except that 4 appears to have a larger β0[S] value than 5. However, the difference is within the estimated error limit of ±20%. Also as for the HRS data, changing the helquat unit leads to variations in β0[S] that are generally not statistically significant. Comparing the β0 values for 1–10 with those of [DAS]PF6 reveals that a number of the new dye salts show a similar level of NLO activity, while several compare favourably. In



Page 10 of 30

10 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

particular, 4, 5, 9 and 10 show β0[S] responses twice as large or even greater when compared with this benchmark compound. These enhancements are due to a combination of decreasing Emax and increasing ∆µ12. These observations provide a strong incentive to pursue further crystalline materials incorporating these new helquat cations, in which large bulk NLO effects can be anticipated.

β0 values calculated via DFT are shown in Table 2. Such data may be of limited reliability (especially in terms of absolute magnitudes),16 so should be treated with some caution. Nevertheless, neither HRS nor Stark studies give information about the contributions of the various tensor components, so it is helpful to have some indication of these. As noted previously for purely organic16 and ruthenium-based16,17 chromophores, βtot increases substantially on moving from the gas phase to MeCN solution. βtot is also larger for the [5]helquat 1′′ than for the [6]helquat 6′′ or for DAS+, differences that are reflected only partially in the experimental data (Table 1). With the x-axis aligned approximately with the dipole of the stilbazolium unit (Supporting Information, Figure S4), the βx and βxxx components dominate as expected. The hyperpolarizability of the pseudolinear DAS+ cation is essentially one-dimensional. In contrast, the off-diagonal βxxy components are relatively significant in 1′′, but less important in 6′′. The nondipolar βxyz terms are predicted to be zero for DAS+, but still only small in its helquat relatives, which is perhaps disappointing. However, this result can be attributed to the fact that these first-generation helquat units are only partially π-conjugated, unlike helicenes. Replacing the quaternising ethylenes with vinyl linkages will enhance conjugation and give more substantial βxyz responses.


Page 11 of 30

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48


11 Table 2. Static first hyperpolarizabilities (10–30 esu) calculated at the CAM-B3LYP/6-311G(d) level for the cations 1′′, 6′′ and DAS+ Cation βxxx

βxxy

βxyy

βyyy

βxxz

βxyz

βyyz

βxzz

βyzz

βzzz

βx

βy

βz

βtot

1′′a 1′′b 6′′a 6′′b DAS+ a DAS+ b

–45.7 –180.4 –11.8 –21.8 –5.7 –8.7

9.7 32.5 –1.7 –0.5 5.2 13.8

3.9 2.4 –9.3 –22.7 –0.1 –0.9

29.6 72.3 29.4 86.3 0.3 0.5

–1.5 –11.3 –1.6 –3.4 0.0 0.0

2.2 4.1 –0.3 0.6 –0.1 –0.2

1.3 0.6 –3.1 –9.8 0.2 0.6

1.8 2.8 0.5 1.5 0.0 –0.1

1.2 2.1 0.0 0.6 0.1 0.2

246.6 616.1 –211.4 –461.6 –187.6 –496.9

–39.9 –175.2 –20.7 –43.0 –5.9 –9.7

32.9 78.5 29.2 87.5 0.3 0.5

252 645 214 472 188 497

a

235.6 582.9 –206.6 –451.3 –193.0 –511.3

In the gas phase. b In MeCN.



Page 12 of 30

12 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

CONCLUSIONS

In summary, we introduce an original class of dicationic helical dyes with strong NLO responses. Notably, both HRS and Stark spectroscopy show that the helquat dye salts 4, 5, 9 and 10 exhibit nonresonant NLO activity significantly higher than [DAS]PF6. Such activities are more than sufficient for potential applications. DFT confirms that the β0 values of the cations in 1 and 6 are strongly competitive, but βxyz components are only small due to limited

π-conjugation. Helical cationic dyes are therefore a highly attractive platform for developing new systems with substantial NLO responses.

EXPERIMENTAL SECTION EXPERIMENTAL SECTION General Methods. Liquids and solutions were transferred via needle and syringe under inert atmosphere unless stated otherwise. N-alkylation reactions and Knoevenagel condensations were run in vessels covered with Alufoil in order to prevent prolonged exposure of the organic cations to ambient light. Melting points were determined on a micro melting point apparatus and are uncorrected. Thin-layer chromatography (TLC) analysis was performed on silica gel plates (Silica gel 60 F254-coated aluminium sheets) and visualized by UV (UV lamp 254/365 nm) and/or chemical staining with KMnO4 [KMnO4 (1% aq.), Na2CO3 (2% aq.)]. TLC analysis of dications was achieved using Stoddart’s magic mixture18 (MeOH/NH4Cl aq (2M)/MeNO2 7:2:1) as eluent on silica gel plates. NMR spectra were measured at 600 MHz for 1H, 151 MHz for

13

C) or at 400 MHz for 1H, 101 MHz for

13

C. In 1H and

13

C NMR

spectra, chemical shifts are referenced as follows (ppm): in acetone-d6 the peaks were referenced relative to the solvent peak δH = 2.09 ppm and δC = 29.80 ppm; and acetonitrile-d3 relative to the solvent peak δH = 1.94 ppm and δC = 118.26 ppm. Chemical shifts are given in δ-scale as parts per million (ppm); coupling constants (J) are given in Hertz. High-resolution mass spectra (HRMS) were obtained with a hybrid FT mass spectrometer using electrospray (+ mode) ionization technique and linear ion trap MS in combination with the orbitrap mass analyzer. The mobile phase consisted of MeOH/water (9:1), flow rate of 200 µL min–1. The sample was dissolved, diluted with the mobile phase and injected using a 5 µL loop. Spray


Page 13 of 30


13 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

voltage, capillary voltage, tube lens voltage and capillary temperature were 5.5 kV, 5 V, 80 V and 275 °C, respectively. High-resolution mass spectra (HRMS) were obtained with the ESI instrument. Dichloromethane (DCM) and triethylamine were purified via distillation under argon over CaH2 and were used directly after distillation. MeOH was distilled from Mg/I2 as follows. MeOH (100 mL) was charged into a 1 L round-bottomed flask. Then, 5 g of Mg was added followed by addition of I2 (500 mg). The mixture was heated to reflux under Ar atmosphere for 15 min. Then, more I2 (500 mg) and MeOH (500 mL) were added and the mixture was refluxed under Ar atmosphere for 2 h. MeOH was then stored under Ar atmosphere over 4 Å activated molecular sieves. Degassed solvents were obtained via the freeze-pump-thaw method. The solvent was frozen under argon, and then thawed under vacuum. This process was repeated three times. Finally the thawed solvent was purged with argon. Unless otherwise stated, all other starting materials and reagents were obtained from commercial suppliers and used without further purification. Synthesis of [5]helquat dyes 1–5 (E)-2-(4-(Dimethylamino)styryl)-6,7,10,11-tetrahydrodipyrido[2,1-a:1',2'k][2,9]phenanthroline-5,12-diium Trifluoromethanesulfonate (1). Methyl-substituted [5]helquat (87 mg, 0.145 mmol) and the aldehyde (43 mg, 0.288 mmol, 2.0 equiv) were placed in a Schlenk flask and put under an argon atmosphere. MeOH (2 mL) was added and the solids dissolved while stirring. Then, the flask was covered with Alufoil and pyrrolidine (115 µL, 100 mg, 1.400 mmol, 9.7 equiv) was added at once. The mixture was stirred at RT for 2 h, when the disappearance of the starting helquat was detected. The reaction was quenched with Et2O (20 mL) causing precipitation. The suspension was centrifuged and the supernatant was separated. The solid residue was then dissolved in MeOH (1 mL) and product precipitated by addition of Et2O (10 mL). The resulting suspension was centrifuged and the supernatant was separated. The resulting solid was dissolved in MeOH (1 mL) and the precipitation procedure was repeated (with 10 mL of Et2O). Finally, the solid was separated and dried in vacuum giving pure [5]helquat dye 1. Dark violet solid. Mp: 177179°C. Yield: 97 mg, 92%. 1H NMR (400 MHz, CD3CN): δ 3.03 (s, 6H), 3.21–3.38 (m, 4H), 4.54–4.98 (m, 4H), 6.74 (d, J = 9.0 Hz, 2H), 6.83 (d, J = 16.0 Hz, 1H), 7.38–7.47 (m, 3H), 7.67 (d, J = 1.9 Hz, 1H), 7.70 (s, 2H), 7.80 (dd, J = 2.0, 6.7 Hz, 1H), 7.87–7.92 (m, 1H), 8.03–8.07 (m, 1H), 8.15–8.21 (m, 1H), 8.46 (d, J = 6.8 Hz, 1H), 8.81–8.85 (m, 1H). 13C NMR (100 MHz, CD3CN): δ 28.2, 28.8, 40.4, 54.5, 56.3, 113.1, 117.6, 121.1, 121.3, 123.3, 123.5, 126.3, 127.0, 127.5, 127.9, 131.0, 131.4, 133.2, 133.7, 141.6, 143.8, 145.4, 145.7, 146.5, 147.0, 148.3, 153.7, 155.5. Elemental analysis: (%) calcd for [C32H29F6N3O6S2] C (52.67), H



Page 14 of 30

14 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

~ (4.01), N (5.76), found C (52.20), H (3.90), N (5.59). IR (neat): ν 3091, 1640, 1580, 1513, 1442, 1262, 1229, 1165, 1033, 640, 519. MS (ESI): m/z (%) 580 (59), 430 (100). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C31H29F3N3O3S) 580.1876, found 580.1873. (E)-2-(2-(2,3,6,7-Tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)vinyl)-6,7,10,11tetrahydrodipyrido[2,1-a:1',2'-k][2,9]phenanthroline-5,12-diium Trifluoromethanesulfonate (2). This compound was prepared and purified in manner similar to dye 1 using methylsubstituted [5]helquat (50 mg, 0.084 mmol), 9-julolidine carboxaldehyde (34 mg, 0.169 mmol, 2.0 equiv), MeOH (4 mL) and pyrrolidine (84 µL, 73 mg, 1.022 mmol, 12.0 equiv). Precipitation was performed with Et2O (40 mL). Re-precipitation was performed twice using MeOH (1 mL) and addition of Et2O (10 mL). Dark blue solid. Mp: 195-197°C. Yield: 60 mg, 92%. 1H NMR (400 MHz, CD3CN): δ 1.86–1.94 (m, 4H), 2.69 (t, J = 6.3 Hz, 4H), 3.21–3.34 (m, 8H), 4.49–4.97 (m, 4H), 6.69 (d, J = 15.9 Hz, 1H), 6.99 (s, 2H), 7.29 (d, J = 15.9 Hz, 1H), 7.56 (d, J = 2.0 Hz, 1H), 7.68–7.71 (m, 3H), 7.86–7.92 (m, 1H), 8.02–8.06 (m, 1H), 8.14– 8.20 (m, 1H), 8.36 (d, J = 6.8 Hz, 1H), 8.80 (m, 1H). 13C NMR (100 MHz, CD3CN): δ 22.2, 28.2, 28.4, 28.9, 50.7, 54.2, 56.3, 116.1, 120.5, 121.1, 122.4, 122.5, 123.2, 126.0, 126.9, 127.4, 128.0, 129.3, 131.0, 133.0, 133.7, 141.5, 144.3, 145.0, 145.5, 146.1, 147.0, 147.1, 148.4, 155.4. Elemental analysis: (%) calcd for [C36H33F6N3O6S2] C (55.31), H (4.25), N

~ (5.37), found C (54.83), H (4.14), N (5.05). IR (neat): ν 3095, 1638, 1571, 1513, 1472, 1261, 1227, 1211, 1154, 1032, 639, 575. MS (ESI): m/z (%) 632 (26), 241 (100). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C35H33F3N3O3S) 632.2189, found 632.2188. (E)-2-(2-(6-(Dimethylamino)naphthalen-2-yl)vinyl)-6,7,10,11-tetrahydrodipyrido[2,1-a:1',2'k][2,9]phenanthroline-5,12-diium Trifluoromethanesulfonate (3). This compound was prepared and purified in manner similar to dye 1 using methylsubstituted [5]helquat (100 mg, 0.167 mmol), the aldehyde (70 mg, 0.351 mmol, 2.1 equiv), MeOH (10 mL) and pyrrolidine (168 µL, 146 mg, 2.045 mmol, 12.3 equiv). Precipitation was performed with Et2O (50 mL). Re-precipitation was performed twice using MeOH (10 mL) and addition of Et2O (50 mL). Dark violet solid. Mp: 212-214°C. Yield: 118 mg, 90%. 1H NMR (400 MHz, CD3CN): δ 3.08 (s, 6H), 3.24–3.36 (m, 4H), 4.59–5.00 (m, 4H), 6.95 (d, J = 2.5 Hz, 1H), 7.10 (d, J = 16.2 Hz, 1H), 7.23 (dd, J = 2.6, 9.1 Hz, 1H), 7.54–7.62 (m, 2H), 7.64 (d, J = 7.6 Hz, 1H), 7.72 (s, 2H), 7.76 (d, J = 9.2 Hz, 1H), 7.80–7.83 (m, 2H), 7.89–7.95 (m, 2H), 8.03–8.07 (m, 1H), 8.16–8.22 (m, 1H), 8.57 (d, J = 6.7 Hz, 1H), 8.84–8.88 (m, 1H). 13C NMR (100 MHz, CD3CN): δ 28.2, 28.6, 40.7, 54.8, 56.3, 106.6, 117.6, 121.1, 121.2, 122.2,


Page 15 of 30


15 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

124.7, 126.9, 127.0, 127.0, 127.6, 127.7, 128.0, 129.4, 130.9, 131.0, 131.9, 133.4, 133.8, 137.7, 141.7, 143.5, 145.8, 145.8, 147.0, 147.1, 148.2, 151.3, 155.1. Elemental analysis: (%) calcd for [C36H31F6N3O6S2.H2O] C (54.20), H (4.17), N (5.27), found C (54.42), H (4.47), N

~ (5.31). IR (neat): ν 3098, 1637, 1594, 1513, 1438, 1262, 1228, 1166, 1127, 1033, 639, 576, 520. MS (ESI): m/z (%) 630 (38), 240 (100). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C35H31F3N3O3S) 630.2033, found 630.2032. 2-((1E,3E)-4-(4-(Dimethylamino)phenyl)buta-1,3-dien-1-yl)-6,7,10,11tetrahydrodipyrido[2,1-a:1',2'-k][2,9]phenanthroline-5,12-diium Trifluoromethanesulfonate (4). This compound was prepared and purified in manner similar to dye 1 using methylsubstituted [5]helquat (134 mg, 0.224 mmol), (E)-3-(4-(dimethylamino)phenyl)acrylaldehyde (78 mg, 0.445 mmol, 2.0 equiv), MeOH (2 mL) and pyrrolidine (224 µL, 194 mg, 2.728 mmol, 12.2 equiv). Precipitation was performed with Et2O (20 mL). Re-precipitation was performed twice using MeOH (2 mL) and addition of Et2O (20 mL). Dark blue solid. Mp: 205-207°C. Yield: 109 mg, 65%. 1H NMR (400 MHz, CD3CN): δ 3.00 (s, 6H), 3.19–3.38 (m, 4H), 4.52–4.98 (m, 4H), 6.41 (d, J = 15.3 Hz, 1H), 6.70–6.75 (m, 2H), 6.80–6.95 (m, 2H), 7.32 (dd, J = 10.3, 15.3 Hz, 1H), 7.40–7.45 (m, 2H), 7.62 (d, J = 1.9 Hz, 1H), 7.71 (s, 2H), 7.76 (dd, J = 2.0, 6.7 Hz, 1H), 7.88–7.93 (m, 1H), 8.00–8.04 (m, 1H), 8.18 (td, J = 8.1, 1.4 Hz, 1H), 8.46 (d, J = 6.7 Hz, 1H), 8.81–8.85 (m, 1H). 13C NMR (100 MHz, CD3CN): δ 28.2, 28.7, 40.4, 54.6, 56.2, 113.1, 121.1, 121.8, 123.3, 123.6, 123.7, 124.7, 126.4, 126.9, 127.6, 127.8, 130.4, 131.0, 133.3, 133.8, 141.6, 141.6, 144.4, 145.1, 145.5, 145.7, 146.6, 147.0, 148.2, 152.9, 155.0. Elemental analysis: (%) calcd for [C34H31F6N3O6S2] C (54.03), H (4.13),

~ N (5.56), found: C (54.10), H (4.11), N (5.51). IR (neat): ν 3094, 1639, 1572, 1515, 1441, 1371, 1279, 1262, 1229, 1151, 1033, 1005, 759, 640, 576. MS (ESI): m/z (%) 606 (14), 228 (100). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C33H31F3N3O3S) 606.2033, found 606.2034. (E)-3-(1,2,3,5,6,7-Hexahydropyrido[3,2,1-ij]quinolin-9-yl)acrylaldehyde (11)14. A previously published procedure14 was followed with some modifications: 9-Julolidine carboxaldehyde

(500

mg,

2.484

mmol,

1.0

equiv),

((1,3-dioxolan-2-

yl)methyl)tributylphosphonium bromide (4.587 g, 12.42 mmol, 5.0 equiv), NaH (60% in mineral oil, 400 mg, 10 mmol, 4.0 equiv) and 18-crown-6 (33 mg, 0.124 mmol, 5 mol%) were charged into an oven-dried Schlenk flask and placed under argon using a vacuum/argon manifold. Under argon atmosphere, THF (20 mL) was added. The mixture was stirred at RT for 2.5 h. After disappearance of 9-julolidine carboxaldehyde was detected (TLC), water (20



Page 16 of 30

16 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

mL) was added and the resulting mixture was extracted with Et2O (3 × 20 mL). The combined organic layers were dried over MgSO4 and filtered through a Celite pad. The Celite pad was washed with Et2O (3 × 5 mL). Volatiles from the filtrate were removed on a rotary evaporator and the crude residue was mixed with THF/10% HCl (1.5:1, 10 mL) and stirred at RT for 0.5 h, until complete consumption of the acetal. The reaction mixture was quenched by addition of water (20 mL) and the resulting solution was extracted with Et2O (3 × 25 mL). The combined ethereal extracts were dried over Na2SO4 and then filtered through a Celite pad. The solid residue after removal of the volatiles was washed with pentane (10 mL) and the resulting aldehyde was dried in vacuum. Mp: 125-127 °C. Yield: 422 mg, 75%. 1H NMR (400 MHz, acetone-d6): δ 1.92-1.99 (m, 4H), 2.73-2.78 (m, 4H), 3.29-3.33 (m, 4H), 6.46 (dd, J = 7.8, 15.5 Hz, 1H), 7.11 (m, 2H), 7.40 (d, J = 15.5 Hz, 1H), 9.56 (d, J = 7.8 Hz, 1H). 13C NMR (100 MHz, acetone-d6): δ 22.2, 28.2, 50.4, 121.7, 121.8, 123.4, 128.9, 146.4, 154.8, 193.2. IR

~ (KBr): ν 837, 1126, 1318, 1451, 1523, 1639, 1654, 3166, 3279. MS (ESI): m/z (%) 228.1 (100), 250.1 (35), 477.2 (15). HRMS (ESI): m/z calcd for (C15H18ON) 228.1383, found 228.1381. 2-((1E,3E)-4-(2,3,6,7-Tetrahydro-1H,5H-pyrido[3,2,1-ij]quinolin-9-yl)buta-1,3-dien-1-yl)6,7,10,11-tetrahydrodipyrido[2,1-a:1',2'-k][2,9]phenanthroline-5,12-diium Trifluoromethanesulfonate (5). This compound was prepared and purified in manner similar to dye 1 using methylsubstituted [5]helquat (43 mg, 0.072 mmol), (E)-3-(1,2,3,5,6,7-hexahydropyrido[3,2,1ij]quinolin-9-yl)acrylaldehyde (33 mg, 0.145 mmol, 2.0 equiv), MeOH (4 mL) and pyrrolidine (72 µL, 62 mg, 0.876 mmol, 12.2 equiv). Precipitation was performed with Et2O (40 mL). Re-precipitation was performed twice using MeOH (4 mL). Dark blue solid. Mp: 225-227°C. Yield: 41 mg, 70%. 1H NMR (400 MHz, CD3CN): δ 1.86–1.96 (m, 4H), 2.69 (t, J = 6.3 Hz, 4H), 3.21–3.34 (m, 8H), 4.49–4.98 (m, 4H), 6.33 (d, J = 15.2 Hz, 1H), 6.70–6.84 (m, 2H), 6.98 (s, 2H), 7.29 (dd, J = 10.0, 15.2 Hz, 1H), 7.55 (d, J = 1.9 Hz, 1H), 7.68–7.74 (m, 3H), 7.87–7.92 (m, 1H), 8.00–8.04 (m, 1H), 8.15–8.21 (m, 1H), 8.40 (d, J = 6.8 Hz, 1H), 8.80–8.84 (m, 1H). 13C NMR (100 MHz, CD3CN): δ 22.4, 28.2, 28.4, 28.8, 50.7, 54.4, 56.3, 121.1, 121.3, 122.4, 122.6, 122.7, 123.3, 123.7, 126.1, 126.9, 127.5, 127.9, 128.3, 131.0, 133.1, 133.7, 141.5, 141.5, 145.2, 145.3, 145.5, 145.6, 146.0, 146.4, 147.0, 148.3, 155.0. Elemental analysis: (%) calcd for [C38H35F6N3O6S2] C (56.50), H (4.37), N (5.20), found C

~ (56.50), H (4.21), N (4.99). IR (neat): ν 3086, 1624, 1563, 1511, 1483, 1269, 1262, 1225,


Page 17 of 30


17 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1209, 1146, 1032, 1029, 756, 640, 573. MS (ESI): m/z (%) 658 (4), 254 (100). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C37H35F3N3O3S) 658.2346, found 658.2347. Synthesis of [6]Helquat Dye Precursor 1-((6-Methylpyridin-2-yl)ethynyl)isoquinoline (12).

[Pd(PPh3)2Cl2] (1.150 g, 1.638 mmol, 5 mol%), CuI (0.622 g, 3.266 mmol, 10 mol%), and 1ethynylisoquinoline (5.000 g, 32.64 mmol, 1.0 equiv) were placed under argon into an ovendried Schlenk flask. Under an argon atmosphere, triethylamine (200 mL) was added followed by 2-bromo-6-methylpyridine (6.737 g, 39.16 mmol, 1.2 equiv). The mixture was stirred under argon while heating at 80–82

o

C for 1 h, when the disappearance of 1-

ethynylisoquinoline was detected. The reaction mixture was allowed to cool to RT, and filtered through a Celite pad. The Celite pad was repeatedly washed with EtOAc, until no product was detected in the eluent (TLC analysis). The volatiles from the filtrate were removed using a rotary evaporator and the crude residue was purified by column chromatography on silica gel using hexane/EtOAc (50:50) as eluent. Brownish solid. Mp: 113–116 °C. Yield: 6.370 g, 80%. 1H NMR (600 MHz, (CD3)2CO): δ 2.61 (s, 3H), 7.39 (d, J = 7.8 Hz, 1H), 7.69 (d, J = 7.6 Hz, 1H), 7.83 (t, J = 7.7 Hz, 1H), 7.86 (ddd, J = 1.2, 6.7, 8.2 Hz, 1H), 7.89 (ddd, J = 1.4, 6.7, 8.3 Hz, 1H), 7.92 (dd, J = 1.3, 5.6 Hz, 1H), 8.08 (ddt, J = 0.8, 1.3, 8.3 Hz, 1H), 8.62 (ddd, J = 0.8, 1.4, 8.2 Hz, 1H), 8.63 (d, J = 5.6 Hz, 1H). 13C NMR (151 MHz, (CD3)2CO): δ 24.5, 85.8, 93.5, 122.0, 124.4, 125.8, 127.2, 128.1, 129.4, 130.3, 131.7, 136.7, 137.6, 142.6, 144.0, 144.2, 160.2. IR (KBr): ~ν 1495, 1552, 1566, 1581, 1619, 2212, 3009, 3054. MS (ESI): m/z (%) 245.1 (100), 246.1 (20), 267.1 (10). HRMS (ESI): m/z calcd for (C17H13N2) 245.1073, found 245.1072. 1-((6-Methyl-1-(pent-3-yn-1-yl)pyridin-1-ium-2-yl)ethynyl)-2-(pent-3-yn-1-yl)isoquinolin-2ium Trifluoromethanesulfonate (13).



Page 18 of 30

18 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

1-((6-Methylpyridin-2-yl)ethynyl)isoquinoline (12, 1.000 g, 4.093 mmol, 1.0 equiv) was charged into an oven-dried Carius tube and put under argon. Under an argon atmosphere, dichloromethane (40 mL) was added followed by pent-3-yn-1-yl trifluoromethanesulfonate10d (4.450 g, 20.586 mmol, 5.0 equiv). The mixture was protected from ambient light with Alufoil cover and stirred at 40–42 °C for 62 h. The reaction mixture was allowed to cool to RT, and then transferred to a round bottomed flask for removal of the volatiles on a rotary evaporator. The residue was washed with Et2O (20 mL) using sonication. The supernatant was separated after centrifugation. This washing, sonication, supernatant removal was repeated two more times (2 × 20 mL Et2O). The resulting solid was extracted using dichloromethane (25 mL) and water (40 mL). The emulsion was sonicated vigorously and then centrifuged. After centrifugation, the dichloromethane layer was taken and washed with water twice (2 × 40 mL). The combined aqueous layers were washed with dichloromethane (2 × 35 mL). The oily residue after complete evaporation of water from the aqueous layer (rotary evaporator) was triturated with Et2O (sonication, 2 × 25 mL) to give a solid. After drying in vacuum, the pure triyne product was obtained. Brownish solid. Mp: 151–154 °C. Yield: 1.23 g, 44%. 1H NMR (600 MHz, (CD3)2CO): δ 1.74 (t, J = 2.6 Hz, 3H), 1.77 (t, J = 2.6 Hz, 3H), 3.27–3.30 (m, 4H), 3.31 (s, 3H), 5.44 (t, J = 6.6 Hz, 2H), 5.50 (t, J = 6.6 Hz, 2H), 8.33 (ddd, J = 1.2, 7.0, 8.5 Hz, 1H), 8.46 (ddd, J = 1.1, 7.0, 8.4 Hz, 1H), 8.46 (dd, J = 1.6, 7.9 Hz, 1H), 8.59 (dt, J = 1.2, 8.4 Hz, 1H), 8.81 (t, J = 7.9 Hz, 1H), 8.90 (dd, J = 1.6, 7.9 Hz, 1H), 8.93 (dd, J = 0.8, 6.8 Hz, 1H), 9.09 (dq, J = 1.0, 8.5 Hz, 1H), 9.20 (d, J = 6.8 Hz, 1H).

13

C NMR (151 MHz,

(CD3)2CO): δ 3.2, 3.2, 20.0, 21.8, 22.0, 56.5, 61.2, 74.2, 74.3, 82.0, 82.2, 90.1, 99.4, 128.6, 129.3, 130.0, 131.0, 133.6, 134.1, 134.4, 136.3, 138.5, 138.5, 138.6, 138.9, 146.3, 160.7. IR ~ (KBr): ν 518, 574, 639, 1031, 1172, 1265, 1491, 1509, 1564, 1581, 1602, 1611, 1619, 2223,

2291, 3092. MS (ESI): m/z (%) 295.1 (4), 296.1 (15), 311.1 (36), 312.1 (10), 377.2 (100), 378.2 (31), 395.2 (13), 527.1 (11). HRMS (ESI): m/z calcd for (C28H26O3N2F3S) 527.1611, found 527.1612. [6]Helquat dye precursor: 6,7,11-Trimethyl-4,5,8,9-tetrahydroisoquinolino[1,2-a]pyrido[1,2k][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (14).


Page 19 of 30


19 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

[Rh(PPh3)3Cl] (0.264 g, 0.285 mmol, 10 mol%) and the dicationic triyne (1.927 g, 2.848 mmol, 1.0 equiv) were charged into an oven-dried Schlenk flask and placed under argon. Under an argon atmosphere, dry and degassed DMF (250 mL) was added. The mixture was stirred at 110–112 °C for 1 h while being protected from ambient light with Alufoil. After complete disappearance of starting material was detected (TLC-mobile phase: Stoddart’s magic mixture18 = MeOH/NH4Cl aq (2M)/MeNO2 7:2:1), the reaction mixture was allowed to cool to RT, and then transferred to a round bottomed flask to remove the solvent on a rotary evaporator. The residue was sonicated with THF (25 mL), and the resulting suspension was transferred to centrifuge tubes. The supernatants were separated after centrifugation. The resulting solid was triturated two more times with THF (sonication, 2 × 25 mL) and finally the solid was triturated three times with Et2O (3 × 20 mL). The resulting solid was dried in vacuum to give pure [6]helquat dye precursor. Light yellow solid. Mp: 241–243 °C. Yield: 1.630 g, 85%. 1H NMR (600 MHz, (CD3)2CO): δ 2.66 (s, 6H), 3.16 (s, 3H), 3.38 (dt, J = 4.8, 15.7 Hz, 1H), 3.48 (dt, J = 4.5, 15.3 Hz, 1H), 3.81 (ddd, J = 1.7, 3.6, 17.0 Hz, 1H), 3.83 (ddd, J = 1.9, 3.7, 17.0 Hz, 1H), 5.10 (dt, 3.7, 14.4 Hz, 1H), 5.17 (dt, J = 3.6, 14.0 Hz, 1H), 5.39 (ddd, J = 1.7, 4.5, 14.0 Hz, 1H), 5.59 (ddd, J = 1.9, 4.8, 14.2 Hz, 1H), 7.48 (dd, J = 2.7, 6.8 Hz, 1H), 7.74 (t, J = 7.4 Hz, 1H), 7.76 (dd, J = 2.7, 7.8 Hz, 1H), 7.83 (ddd, J = 1.2, 6.9, 8.7 Hz, 1H), 7.99 (ddd, J = 1.1, 6.9, 8.1 Hz, 1H), 8.09 (dq, J = 0.8, 8.7 Hz, 1H), 8.29 (d, J = 8.1 Hz, 1H), 8.55 (d, J = 6.7 Hz, 1H), 9.03 (d, J = 6.7 Hz, 1H). 13C NMR (151 MHz, acetone-d6): δ 16.8, 17.0, 21.4, 26.0, 26.9, 50.2, 56.2, 123.8, 125.9, 127.0, 128.7, 128.8, 128.9, 129.2, 129.2, 132.8, 136.2, 137.6, 138.9, 140.0, 141.1, 142.0, 142.6, 144.4, 148.9, 151.7, 157.0. Elemental analysis: (%) calcd for [C29H26F6N2O6S2] C (51.48), H (3.87), N (4.14), found C (51.07), H (3.95), N (4.00). IR (KBr): ~ν 518, 638, 1031, 1154, 1265, 1491, 1509, 1564, 1581, 1602, 1611, 1619, 3080. MS (ESI): m/z (%) 181.6 (4), 377.2 (100), 378.2 (34), 527.2 (4). HRMS (ESI): m/z calcd for [(M – CF3SO3–)+] (C28H26F3N2O3S) 527.1611, found 527.1612. Synthesis of [6]Helquat Dyes 6 - 10. (E)-11-(4-(Dimethylamino)styryl)-6,7-dimethyl-4,5,8,9-tetrahydroisoquinolino[1,2a]pyrido[1,2-k][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (6). [6]Helquat dye precursor (70 mg, 0.103 mmol, 1.0 equiv) and 4-dimethylaminobenzaldehyde (47 mg, 0.315 mmol, 3.1 equiv) were charged into a Schlenk flask and placed under argon. Dry MeOH (7.0 mL) was added to the reaction mixture followed by pyrrolidine (100 µL, 87 mg, 1.217 mmol, 11.8 equiv). The flask was covered with Alufoil and the reaction mixture



Page 20 of 30

20 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

was stirred at RT for 1 h. The progress of the reaction was monitored by TLC (Stoddart’s magic mixture, starting helquat Rf = 0.5, product Rf = 0.75). The reaction was quenched by addition of Et2O (24 mL) and a purple colored solid precipitated. The suspension was sonicated for 2 min and then centrifuged. The supernatant was separated from the solid. The solid was further purified by dissolution in MeOH (2 mL) and precipitation by adding Et2O (16 mL). The suspension was sonicated, centrifuged and the supernatant was separated. This dissolution, precipitation procedure was repeated two more times. After drying in vacuum, [6]helquat dye 6 was obtained as a purple solid. Mp: >350 °C. Yield: 56 mg (67%). 1H NMR (600 MHz, (CD3)2CO): δ 2.66 (s, 3H), 2.66 (s, 3H), 3.15 (s, 6H), 3.34 (ddd, J = 4.2, 14.4, 17.3 Hz, 1H), 3.48 (dt, J = 4.0, 16.2 Hz, 1H), 3.82 (dt, J = 3.7, 16.8 Hz, 1H), 3.82 (dt, J = 3.5, 16.8 Hz, 1H), 5.12 (dt, J = 3.7, 14.2 Hz, 1H), 5.17 (dt, J = 3.5, 14.7 Hz, 1H), 5.40 (dd, J = 4.0, 13.5 Hz, 1H), 5.68 (ddd, J = 1.6, 4.2, 13.3 Hz, 1H), 6.87–6.90 (m, 2H), 7.3 (d, J = 8.0 Hz, 1H), 7.63 (t, J = 8.1 Hz, 1H), 7.68 (d, J = 15.6 Hz, 1H), 7.77–7.80 (m, 2H) 7.82 (d, J = 15.6 Hz, 1H), 7.84 (ddd, J = 1.2, 7.0, 8.5 Hz, 1H), 7.99 (dd, J = 7.0, 8.2 Hz, 1H), 8.07 (d, J = 8.2 Hz, 1H), 8.13 (d, J = 8.5 Hz, 1H), 8.29 (d, J = 8.2 Hz, 1H), 8.55 (d, J = 6.7 Hz, 1H), 9.04 (d, J = 6.7 Hz, 1H)..

13

C NMR (151 MHz, (CD3)2CO): δ 16.8, 16.9, 26.2, 26.8, 40.1, 49.9, 56.2,

111.9, 112.8, 123.4, 123.6, 124.3, 125.7, 126.9, 127.6, 128.8, 129.1, 129.2, 131.8, 132.6, 136.1, 137.4, 138.6, 139.8, 140.5, 141.7, 142.3, 142.5, 146.5, 147.6, 151.9, 153.7, 155.9. Elemental analysis: (%) calcd for [C38H35F6N3O6S2.0.5H2O] C (55.88), H (4.44), N (5.14),

~ found C (55.75), H (4.35), N (5.20). IR (KBr): ν 3076, 1591, 1555, 1530, 1269, 1164, 1030, 638, 573, 517. MS (ESI): m/z (%) 658.2 (5), 508.3 (10), 375.2 (3), 255.1 (20), 254.6 (100), 247.6 (8), 194.0 (7). HRMS (ESI): m/z calcd for [(M – TfO)+] (C37H35O3N3F3S) 658.2346, found 658.2344. (E)-11-(2-(1,2,3,5,6,7-Hexahydropyrido[3,2,1-ij]quinolin-9-yl)vinyl)-6,7-dimethyl-4,5,8,9tetrahydroisoquinolino[1,2-a]pyrido[1,2-][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (7). [6]Helquat dye 7 was prepared and purified in manner similar to compound 6 using [6]helquat dye precursor (70 mg, 0.103 mmol, 1.0 equiv), 9-julolidinecarbaldehyde (147 mg, 0.730 mmol, 7.1 equiv), dry MeOH (7.0 mL) and pyrrolidine (100 μL, 87 mg, 1.217 mmol, 11.8 equiv). The reaction time was 2.5 h. A purple colored solid was precipitated by addition of Et2O (56 mL). Re-precipitation was performed three times using MeOH (3 mL) and addition of Et2O (24 mL). Purple solid. Mp: >350 °C. Yield: 41 mg (46%). 1H NMR (600 MHz, (CD3)2CO): δ 1.98–2.03 (m, 4H), 2.65 (s, 3H), 2.66 (s, 3H), 2.79–2.83 (m, 4H), 3.30 (ddd, J =


Page 21 of 30


21 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

3.7, 14.2, 17.0 Hz, 1H), 3.38–3.41 (m, 4H), 3.47 (ddd, J = 3.7, 14.5, 17.0 Hz, 1H), 3.80 (ddd, J = 1.9, 4.7, 17.0 Hz, 1H), 3.82 (ddd, J = 1.9, 4.9, 17.0 Hz, 1H), 5.04 (dt, J = 3.7, 14.0 Hz, 1H), 5.16 (dt, J = 3.7, 14.3 Hz, 1H), 5.39 (ddd, J = 1.9, 4.7, 14.0 Hz, 1H), 5.60 (ddd, J = 1.9, 4.9, 13.8 Hz, 1H), 7.20 (dd, J = 1.2, 8.0 Hz, 1H), 7.34 (s, 2H), 7.55 (t, J = 8.1 Hz, 1H), 7.73 (d, J = 15.5 Hz, 1H), 7.82 (ddd, J = 1.2, 6.9, 8.8 Hz, 1H), 7.84 (d, J = 15.5 Hz, 1H), 7.98 (ddd, J = 1.1, 6.9, 8.1 Hz, 1H), 8.01 (dd, J = 1.2, 8.2 Hz, 1H), 8.11 (dq, J = 0.9, 8.8 Hz, 1H), 8.28 (d, J = 8.1 Hz, 1H), 8.53 (d, J = 6.8 Hz, 1H), 9.02 (d, J = 6.8 Hz, 1H). 13C NMR (151 MHz, (CD3)2CO): δ 16.7, 16.9, 22.1, 26.2, 26.8, 28.3, 49.6, 50.6, 56.2, 110.1, 122.1, 122.5, 123.6, 123.8, 125.6, 126.9, 126.9, 128.8, 129.1, 129.4, 129.7, 132.5, 136.1, 137.4, 138.6, 139.8, 140.3, 141.7, 141.9, 142.2, 147.0, 147.1, 147.3, 152.0, 156.0. Elemental analysis: (%) calcd for [C42H39F6N3O6S2] C (58.66), H (4.57), N (4.89), found C (58.42), H (4.88), N (4.40). IR

~ (KBr): ν 3074, 1627, 1588, 1553, 1524, 1484, 1260, 1163, 1030, 638, 573, 517. MS (ESI): m/z (%) 710.4 (14), 561.4 (8), 475.4 (6), 453.4 (10), 362.3 (7), 280.7 (100), 217.1 (4). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C41H39N3O3F3S) 710.2659, found 710.2653. (E)-11-(2-(6-(Dimethylamino)naphthalen-2-yl)vinyl)-6,7-dimethyl-4,5,8,9tetrahydroisoquinolino[1,2-a]pyrido[1,2-k][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (8). [6]Helquat dye 8 was prepared and purified in manner similar to compound 6 using [6]helquat dye precursor (75 mg, 0.111 mmol, 1.0 equiv), 6-dimethylaminonaphthylaldehyde (66 mg, 0.331 mmol, 3.0 equiv), dry MeOH (7.5 mL) and pyrrolidine (107 µL, 93 mg, 1.302 mmol, 11.7 equiv). A red colored solid precipitated after the addition of Et2O (60 mL). Reprecipitation was performed three times using MeOH (10 mL). Dark red solid. Mp: >350 °C. Yield: 71 mg (75%). 1H NMR (600 MHz, CD3CN): δ 2.53 (s, 3H), 2.55 (s, 3H), 3.05 (ddd, J = 4.9, 14.3, 17.1 Hz, 1H), 3.11 (s, 6H), 3.16 (ddd, J = 4.6, 14.6, 17.2 Hz, 1H), 3.54 (ddd, J = 1.8, 3.5, 17.2 Hz, 1H), 3.58 (ddd, J = 1.9, 3.8, 17.1 Hz, 1H), 4.70 (dt, J = 3.8, 14.0 Hz, 1H), 4.79 (dt, J = 3.5, 14.3 Hz, 1H), 5.01 (ddd, J = 1.8, 4.6, 13.9 Hz, 1H), 5.38 (ddd, J = 1.9, 4.9, 13.8 Hz, 1H), 6.82 (dd, J = 1.3, 8.0 Hz, 1H), 7.01 (d, J = 2.6 Hz, 1H), 7.27 (dd, J = 2.6, 9.1 Hz, 1H), 7.49 (t, J = 8.1 Hz, 1H), 7.58 (d, J = 15.8 Hz, 1H), 7.65 (ddd, J = 1.3, 6.9, 8.8 Hz, 1H), 7.74 (d, J = 15.8 Hz, 1H), 7.77 (d, J = 8.7 Hz, 1H), 7.80 (dq, J = 1.0, 8.8 Hz, 1H), 7.82 (d, J = 9.1 Hz, 1H), 7.83 (dd, J = 1.3, 8.3 Hz, 1H), 7.86 (dd, J = 2.0, 8.7 Hz, 1H), 7.88 (ddd, J =1.1, 6.9, 8.1 Hz, 1H), 8.03 (d, J = 2.1 Hz, 1H), 8.12 (d, J = 8.1 Hz, 1H), 8.30 (d, J = 6.7 Hz, 1H), 8.60 (d, J = 6.7 Hz, 1H).

13

C NMR (151 MHz, CD3CN): δ 17.1, 17.2, 26.1, 26.8, 40.7,

50.3, 56.1, 106.6, 115.6, 117.7, 123.5, 125.0, 125.2, 126.0, 126.8, 127.1, 128.1, 128.3, 128.6, 128.9, 129.1, 129.3, 131.0, 132.4, 132.8, 136.5, 137.0, 137.9, 138.7, 140.0, 141.1, 142.3,



Page 22 of 30

22 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

142.4, 143.1, 146.3, 148.1, 151.4, 151.4, 155.5. Elemental analysis: calcd for [C42H37F6N3O6S2] C (58.80), H (4.35), N (4.90), found: C (58.56), H (4.37), N (4.79). IR

~ (KBr): ν 3081, 1622, 1599, 1560, 1508, 1484, 1263, 1154, 1031, 639, 573, 518. MS (ESI): m/z (%) 708.5 (68), 559.5 (25), 558.5 (50), 375.3 (7), 279.7 (100), 280.2 (48), 194.2 (7). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C41H37O3N3F3S) 708.2502, found 708.2505. 11-((1E,3E)-4-(4-(Dimethylamino)phenyl)buta-1,3-dien-1-yl)-6,7-dimethyl-4,5,8,9tetrahydroisoquinolino[1,2-a]pyrido[1,2-k][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (9). [6]Helquat dye 9 was prepared and purified similarly to compound 6 using [6]helquat dye precursor (100 mg, 0.148 mmol, 1.0 equiv), 4-dimethylaminocinnamaldehyde (78 mg, 0.445 mmol, 3.0 equiv), dry MeOH (10.0 mL) and pyrrolidine (143 µL, 124 mg, 1.741 mmol, 11.8 equiv). The reaction time was 0.5 h. The addition of Et2O (80 mL) gave a purple colored precipitate. Re-precipitation was performed three times using MeOH (5 mL) and addition of Et2O (40 mL). Purple solid. Mp: >350 °C. Yield: 72 mg (58%). 1H NMR (600 MHz, (CD3)2CO): δ 2.66 (s, 3H), 2.67 (s, 3H), 3.10 (s, 6H), 3.48 (ddd, J = 4.8, 14.4, 17.1 Hz, 1H), 3.51 (ddd, J = 4.5, 14.5, 17.0 Hz, 1H), 3.81 (ddd, J = 1.9, 3.8, 17.0 Hz, 1H), 3.86 (ddd, J = 1.9, 3.6, 17.1 Hz, 1H), 5.07 (dt, J = 3.6, 14.0 Hz, 1H), 5.18 (dt, J = 3.8, 13.8 Hz, 1H), 5.40 (ddd, J = 1.9, 4.5, 14.0 Hz, 1H), 5.60 (ddd, J = 1.9, 4.8, 13.6 Hz, 1H), 6.82–6.84 (m, 2H), 7.16 (d, J = 15.3 Hz, 1H), 7.21 (dd, J = 10.0, 15.3 Hz, 1H), 7.30 (dd, J = 1.3, 7.9 Hz, 1H), 7.34 (d, J = 14.9 Hz, 1H), 7.52–7.55 (m, 2H), 7.61 (t, J = 8.1 Hz, 1H), 7.74 (dd, J = 10.0, 14.9 Hz, 1H), 7.81 (ddd, J = 1.2, 6.9, 8.8 Hz, 1H), 8.00 (ddd, J = 1.1, 6.9, 8.1 Hz, 1H), 8.04 (dd, J = 1.3, 8.3 Hz, 1H), 8.14 (dq, J = 0.9, 8.8 Hz, 1H), 8.29 (d, J = 8.1 Hz, 1H), 8.55 (d, J = 6.7 Hz, 1H), 9.03 (d, J = 6.7 Hz, 1H). 13C NMR (151 MHz, (CD3)2CO): δ 16.8, 16.9, 26.2, 26.9, 40.2, 49.8, 56.3, 113.0, 117.6, 123.6, 123.7, 124.4, 124.7, 125.8, 127.0, 128.0, 128.8, 129.2, 129.2, 130.4, 132.5, 136.2, 137.5, 138.6, 140.0, 140.7, 141.9, 142.5, 142.7, 145.1, 147.6, 147.9, 152.0, 152.9, 155.3. Elemental analysis: calcd for [C40H37F6N3O6S2] C (57.62), H (4.47), N

~ (5.04), found: C (57.11), H (4.78), N (5.11). IR (KBr): ν 3076, 1626, 1583, 1552, 1527, 1483, 1263, 1153, 1031, 638, 573, 518. MS (ESI): m/z (%) 684.5 (7), 535.5 (13), 534.5 (40), 402.4 (12), 401.4 (17), 377.3 (10), 362.3 (8), 268.2 (43), 267.7 (100), 194.1 (21). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C39H37O3N3F3S) 684.2502, found 684.2500. 11-((1E,3E)-4-(1,2,3,5,6,7-Hexahydropyrido[3,2,1-ij]quinolin-9-yl)buta-1,3-dien-1-yl)-6,7dimethyl-4,5,8,9-tetrahydroisoquinolino[1,2-a]pyrido[1,2-k][2,9]phenanthroline-3,10-diium Trifluoromethanesulfonate (10).


Page 23 of 30


23 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

[6]Helquat dye 10 was prepared and purified similarly to compound 6 using [6]helquat dye precursor (70 mg, 0.103 mmol, 1.0 equiv), (E)-3-(1,2,3,5,6,7-hexahydropyrido[3,2,1ij]quinolin-9-yl)acrylaldehyde (70 mg, 0.308 mmol, 3.0 equiv), dry MeOH (7.0 mL) and pyrrolidine (100 µL, 87 mg, 1.217 mmol, 11.8 equiv). The reaction was completed in 2.5 h. The addition of Et2O (56 mL) gave a deep blue colored precipitate. Re-precipitation was performed three times using MeOH (10 mL) and addition of Et2O (60 mL). Deep blue solid. Mp: >350 °C. Yield: 37 mg (41%). 1H NMR (600 MHz, (CD3)2CO): δ 1.96–2.01 (m, 4H), 2.65 (s, 3H), 2.66 (s, 3H), 2.77 (t, J = 6.4 Hz, 4H), 3.32–3.35 (m, 4H), 3.33 (ddd, J = 4.8, 14.5, 17.2 Hz, 1H), 3.47 (ddd, J = 4.6, 14.2, 17.0 Hz, 1H), 3.80 (ddd, J = 1.8, 3.5, 17.0 Hz, 1H), 3.84 (ddd, J = 1.9, 3.5, 17.2 Hz, 1H), 5.04 (dt, J = 3.5, 14.2 Hz, 1H), 5.16 (dt, J = 3.5, 14.0 Hz, 1H), 5.39 (ddd, J = 1.8, 4.6, 13.8 Hz, 1H), 5.55 (ddd, J = 1.9, 4.8, 13.9 Hz, 1H), 7.05 (d, J = 15.1 Hz, 1H), 7.08 (d, J = 0.6 Hz, 2H), 7.14 (ddd, J = 0.7, 10.7, 15.1 Hz, 1H), 7.26 (dd, J = 1.3, 7.9 Hz, 1H), 7.26 (d, J = 14.8 Hz, 1H), 7.59 (t, J = 8.1 Hz, 1H), 7.74 (dd, J = 10.7, 14.8 Hz, 1H), 7.80 (ddd, J = 1.3, 7.0, 8.8 Hz, 1H), 8.00 (ddd, J = 1.1, 7.0, 8.1 Hz, 1H), 8.01 (dd, J = 1.3, 8.4 Hz, 1H), 8.13 (dq, J = 0.9, 8.8 Hz, 1H), 8.29 (ddt, J = 0.7, 1.3, 8.1 Hz, 1H), 8.54 (dd, J = 0.9, 6.7 Hz, 1H), 9.03 (d, J = 6,7 Hz, 1H). 13C NMR (151 MHz, (CD3)2CO): δ 16.8, 16.9, 22.3, 26.1, 26.8, 28.3, 49.5, 50.5, 56.2, 116.4, 121.3, 122.1, 122.6, 123.6, 124.1, 125.7, 126.9, 127.5, 128.2, 128.8, 129.1, 129.2, 132.5, 136.1, 137.4, 138.5, 139.8, 140.4, 141.7, 142.2, 142.3, 145.9, 145.9, 147.6, 147.9, 151.9, 155.2. Elemental analysis: calcd for [C44H41F6N3O6S2] C (59.65), H (4.66), N (4.74), found C (59.48), H (4.30), N (4.12). IR

~ (KBr): ν 3074, 1627, 1588, 1553, 1524, 1484, 1260, 1163, 1030, 638, 573, 517. MS (ESI) m/z: 736.3 (43), 586.4 (42), 401.2 (11), 294.2 (50), 293.7 (100), 279.7 (22), 194.1 (22), 186.2 (8). HRMS (ESI): m/z calcd for [(M – TfO–)+] (C43H41F3N3O3S) 736.2815, found 736.2812. Hyper-Rayleigh Scattering General details of the HRS experiment have been discussed elsewhere,19 and the apparatus and experimental procedures used for the fs studies were exactly as described previously.11 These measurements were carried out in MeCN, and the reference compound was crystal violet (octupolar βyyy,800 = 500 × 10–30 esu in MeCN; from the value of 340 × 10–30 esu in MeOH, corrected for local field factors at optical frequencies). For all measurements, dilute solutions (1–5 × 10–5 M) were used to ensure a linear dependence of I2ω/Iω2 on concentration, precluding the need for Lambert-Beer correction factors. The absence of demodulation at 800 nm, i.e. constant values of β versus frequency, confirmed that no fluorescence contributions to the HRS signals were present at 400 nm for most of the compounds. Some fluorescence was



Page 24 of 30

24 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

detected for the salts 2 and 6–8, but this has been accounted for by the data processing protocol used. The reported β values are the averages taken from measurements at different amplitude modulation frequencies (80, 160, 240 MHz and also 320 MHz in some cases). Stark Spectroscopy The Stark apparatus, experimental methods and data collection procedure were as previously reported,20 except that a Xe arc lamp was used as the light source instead of a W filament bulb. The Stark spectrum for each compound was measured at least twice. The data analysis was carried out as previously described,20 by using the zeroth, first and second derivatives of the absorption spectrum for analysis of the Stark ∆ε(ν) spectrum in terms of the Liptay treatment.15 The dipole-moment change, ∆µ12 = µe – µg, where µe and µg are the respective excited and ground-state dipole moments, was then calculated from the coefficient of the second derivative component. PrCN was used as the glassing medium, for which the local field correction fint is estimated as 1.33. The value of the transition dipole-moment µ12 can be determined from the oscillator strength fos of the transition by eq. 1.

  fos µ12 =   –5 1.08 ×10 E max 

1/2

(1)

where Emax is the energy of the ICT maximum (in wavenumbers) and µ12 is in eÅ. The latter is converted into Debye units on multiplying by 4.803. If the hyperpolarizability β0 tensor has only nonzero elements along the ICT direction, then this quantity is given by eq. 2.

3∆µ12 (µ12 )

2

β0 =

(E max )

2

(2) A relative error of ±20% is estimated for the β0 values derived from the Stark data and using eq 2, while experimental errors of ±10% are estimated for µ12 and ∆µ12. Note that the ±20% uncertainty for the β0 values is merely statistical and does not account for any errors introduced by two-state extrapolation. Theoretical Studies DFT calculations were performed by using the Gaussian 09 program package.21 The geometries of cations 1′′, 6′′ and DAS+ were optimised in the gas phase by using their X-ray crystal structures as starting points.22 The solvent effect of MeCN in the TD-DFT calculations was accounted for by using a CPCM,23 and the UV–vis absorption spectra were simulated by using the GaussSum program24 (curve fwhm = 3000 cm–1).


Page 25 of 30


25 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

The cation 1′′ was optimised and subsequent TD-DFT calculations were carried out by using three different functionals (B3LYP,25 M0626 and CAM-B3LYP27) with the 6-311G(d) basis set. As shown in Figure S1, the visible absorption band contains two transitions when using B3LYP or M06, while CAM-B3LYP predicts the UV–vis spectrum more accurately. In all cases, the calculations overestimate the energy of the visible band. Selected frontier MOs of 1′′ and 6′′ are depicted in Figures S2 and S3, the computed TD-DFT transitions are shown in Table S1, and optimised atomic coordinates in Tables S2 and S3. Static first hyperpolarizabilities calculated for 1′′ in the gas phase and MeCN by using 6-311G(d) with B3LYP, M06 or CAM-B3LYP are shown in Table S4. The optimised structures of 1′′, 6′′ and the DAS+ cation are included in Figure S4 along with the axis convention used.

ASSOCIATED CONTENT Supporting Information The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.joc.XXXXXXX. 1

H, and 13C NMR spectra of all new compounds, crystallographic and theoretical data. CCDC

1012247, 1410502. (PDF)

AUTHOR INFORMATION Corresponding Authors *E-mail: [email protected], [email protected]

Notes The authors declare no competing financial interest.

ACKNOWLEDGMENTS

This work was supported by ASCR (RVO: 61388963, M200551208 to F.T.), the Czech Science Foundation (13-19213S to F.T.), the Fund for Scientific Research-Flanders (Research



Page 26 of 30

26 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Grant 1510712N), the University of Leuven (GOA/2011/03), and the EPSRC (grants EP/G020299/1 and EP/J018635/1 to B.J.C.). B.S.B. acknowledges the Beckman Institute of the California Institute of Technology for support. We thank Mrs. J. Bařinková for her skilful experimental help.

REFERENCES AND NOTES (1) Nonlinear Optical Properties of Matter: From Molecules to Condensed Phases; Papadopoulos, M. G.; Leszczynski, J.; Sadlej, A. J., Eds.; Springer: Dordrecht, 2006. (2) Selected examples: (a) Jeong, J.-H.; Kang, B.-J.; Kim, J.-S.; Jazbinsek, M.; Lee, S.-H.; Lee, S.-C.; Baek, I.-H.; Yun, H.; Kim, J.; Lee, Y. S.; Lee, J.-H.; Kim, J.-H.; Rotermund, F.; Kwon, O-P. Sci. Rep. 2013, 3, 3200. (b) McEntee, J. Chem. World 2007, March, 52–56. (c) www.teraview.com. (3) Concerning DAST: (a) Marinotto, D.; Lucenti, E.; Scavia, G.; Ugo, R.; Tavazzi, S.; Mattei, G. Cariati, E. J. Mater. Chem. C 2014, 2, 8532–8538. (b) Zheng, M.-L.; Fujita, K.; Chen, W.-Q.; Duan, X.-M.; Kawata, S. J. Phys. Chem. C 2011, 115, 8988–8993. (c) Macchi, R.; Cariati, E.; Marinotto, D.; Roberto, D.; Tordin, E.; Ugo, R.; Bozio, R.; Cozzuol, M.; Pedron,

D.;

Mattei,

G.

J.

Mater.

Chem.

2010,

20,

1885–1890.

(d)

www.rainbowphotonics.com. (4) Compounds like DAST: (a) Kim, J.-S.; Jeong, J.-H.; Yun, H.; Jazbinsek, M.; Kim, J. W.; Rotermund, F.; Kwon, O-P. Cryst. Growth Des. 2013, 13, 5085–5091. (b) Kim, P.-J.; Jeong, J.-H.; Jazbinsek, M.; Choi, S.-B.; Baek, I.-H.; Kim, J.-T.; Rotermund, F.; Yun, H.; Lee, Y. S.; Günter, P.; Kwon, O.-P. Adv. Funct. Mater. 2012, 22, 200–209. (c) Nunzi, F.; Fantacci, S.; Cariati, E.; Tordin, E.; Casati, N.; Macchi, P. J. Mater. Chem. 2010, 20, 7652– 7660. (d) Figi, H.; Mutter, L.; Hunziker, C.; Jazbinšek, M.; Günter, P.; Coe, B. J. J. Opt. Soc. Am. B 2008, 25, 1786–1793. (e) Coe, B. J.; Harris, J. A.; Hall, J. J.; Brunschwig, B. S.; Hung, S.-T.; Libaers, W.; Clays, K.; Coles, S. J.; Horton, P. N.; Light, M. E.; Hursthouse, M. B.; Garín, J.; Orduna, J. Chem. Mater. 2006, 18, 5907–5918.


Page 27 of 30


27 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(5) (a) Coe, B. J.; Fielden, J.; Foxon, S. P.; Asselberghs, I.; Clays, K.; Van Cleuvenbergen, S.; Brunschwig, B. S. Organometallics 2011, 30, 5731–5743. (b) Coe, B. J.; Fielden, J.; Foxon, S. P.; Helliwell, M.; Brunschwig, B. S.; Asselberghs, I; Clays, K; Olesiak, J.; Matczyszyn, K.; Samoc, M. J. Phys. Chem. A 2010, 114, 12028–12041. (c) Coe, B. J.; Fielden, J.; Foxon, S. P.; Harris, J. A.; Helliwell, M.; Brunschwig, B. S.; Asselberghs, I.; Clays, K.; Garín, J.; Orduna, J. J. Am. Chem. Soc. 2010, 132, 10498–10512. (d) Coe, B. J.; Harris, J. A.; Brunschwig, B. S.; Garín, J.; Orduna, J. J. Am. Chem. Soc. 2005, 127, 3284– 3285. (6) Verbiest, T.; Elshocht, S. V.; Kauranen, M.; Hellemans, L.; Snauwaert, J.; Nuckolls, C.; Katz, T. J.; Persoons, A. Science 1998, 282, 913–915. (7) Recent selected reviews on helicenes and their congeners: (a) Gingras, M. Chem. Soc. Rev. 2013, 42, 1051-1095. (b) Shen, Y.; Chen, C. F. Chem. Rev. 2012, 112, 1463-1535. (c) Stará, I. G.; Starý, I. In Science of Synthesis; Siegel, J. S.; Tobe, Y., Eds.; Thieme, Stuttgart, 2010; Vol. 45, 885-953. (d) Rajca, A.; Miyasaka, M. In Functional Organic Materials; Müller, T. J. J.; Bunz, U. H. F., Eds.; Wiley-VCH, Weinheim, 2007, 547-581. (8) (a) Torricelli, F.; Bosson, J.; Besnard, C.; Chekini, M.; Bürgi, T.; Lacour, J. Angew. Chem. Int. Ed., 2013 52, 1796-1800. (b) Herse, C.; Bas, D.; Krebs, F. C.; Bürgi, T.; Weber, J.; Wesolowski, T.; Laursen, B. W.; Lacour, J. Angew. Chem. Int. Ed. 2003, 42, 31623166. (c) Bosson, J.; Gouin, J.; Lacour, J. Chem. Soc. Rev., 2014 43, 2824-2840. (9) Racemic Arai’s dyes have been mentioned only in a review and synthetic procedures and other details have not been published. See: Sato, K.; Arai, S. In Cyclophane Chemistry for the 21st Century, Takemura, H., Ed.; Research Signpost, Trivandrum, 2002; p. 173 (see p. 192). (10) (a) Reyes-Gutiérrez, P. E.; Jirásek, M.; Severa, L.; Novotná, P.; Koval, D.; Sázelová, P.; Vávra, J.; Meyer, A.; Císařová, I.; Šaman, D.; Pohl, R.; Štěpánek, P.; Slavíček, P.; Coe, B. J.; Hájek, M.; Kašička, V.; Urbanová, M.; Teplý, F. Chem. Commun. 2015, 51, 1583-1586. Further selected reports on helquats: (b) Adriaenssens, L.; Severa, L.; Šálová, T.; Císařová, I.; Pohl, R.; Šaman, D.; Rocha, S. V.; Finney, N. S.; Pospíšil, L.; Slavíček, P.; Teplý, F. Chem.-Eur. J. 2009, 15, 1072-1076. (c) Pospíšil, L.; Bednárová, L.; Štěpánek, P.;



Page 28 of 30

28 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Slavíček, P.; Vávra, J.; Hromadová, M.; Dlouhá, H.; Tarábek, J.; Teplý, F. J. Am. Chem. Soc. 2014, 136, 10826-10829. (d) Vávra, J.; Severa, L.; Císařová, I.; Klepetářová, B.; Šaman, D.; Koval, D.; Kašička, V.; Teplý, F. J. Org. Chem. 2013, 78, 1329-1342. (11) Olbrechts, G.; Clays, K.; Persoons, A. J. Opt. Soc. Am. B 2000, 17, 1867–1873. (12) (a) Oudar, J. L.; Chemla, D. S. J. Chem. Phys. 1977, 66, 2664–2668. (b) Oudar, J. L. J. Chem. Phys. 1977, 67, 446–457. (13) (a) Clays, K.; Coe, B. J. Chem. Mater. 2003, 15, 642–648. (b) Coe, B. J.; Harris, J. A.; Asselberghs, I.; Wostyn, K.; Clays, K.; Persoons, A.; Brunschwig, B. S.; Coles, S. J.; Gelbrich, T.; Light, M. E.; Hursthouse, M. B.; Nakatani, K. Adv. Funct. Mater. 2003, 13, 347–357. (14) Coe, B. J.; Foxon, S. P.; Harper, E. C.; Harris, J. A.; Helliwell, M.; Raftery, J.; Asselberghs, I.; Clays, K.; Franz, E.; Brunschwig, B. S.; Fitch, A. G. Dyes and Pigments 2009, 82, 171–186. (15) (a) Bublitz, G. U.; Boxer, S. G. Annu. Rev. Phys. Chem. 1997, 48, 213–242. (b) Liptay, W. In Excited States, Vol. 1; Lim, E. C., Ed.; Academic Press, New York, 1974, pp. 129–229. (16) Coe, B. J.; Pilkington, R. A. J. Phys. Chem. A 2014, 118, 2253–2268. (17) Coe, B. J.; Helliwell, M.; Peers, M. K.; Raftery, J.; Rusanova, D.; Clays, K.; Depotter, G.; Brunschwig, B. S. Inorg. Chem. 2014, 53, 3798–3811. (18) Amabilino, D. B.; Ashton, P. R.; Reder, A. S.; Spencer N.; Stoddart, J. F. Angew. Chem. Int. Ed. Engl. 1994, 33, 1286-1290. (19) (a) Hendrickx, E.; Clays, K.; Persoons, A. Acc. Chem. Res. 1998, 31, 675–683. (b) Clays, K.; Persoons, A. Rev. Sci. Instrum. 1992, 63, 3285–3289. (20) (a) Coe, B. J.; Harris, J. A.; Brunschwig, B. S. J. Phys. Chem. A 2002, 106, 897– 905. (b) Shin, Y. K.; Brunschwig, B. S.; Creutz, C.; Sutin, N. J. Phys. Chem. 1996, 100, 8157–8169. (21) Gaussian 09, Revision B.01, Frisch, M. J.; et al. Gaussian, Inc., Wallingford CT, 2010.


Page 29 of 30


29 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

(22) Structures for several salts of DAS+: Sun, Z.-H.; Liu, X.-T.; Wang, X.-Q.; Li, L.N.; Shi, X.-J.; Li, S.-G.; Ji, C.-M.; Luo, J.-H.; Hong, M.-C. Cryst. Growth Des. 2012, 12, 6181–6197. (23) (a) Cossi, M.; Rega, N.; Scalmani, G.; Barone, V. J. Comput. Chem. 2003, 24, 669–681. (b) Barone, V.; Cossi, M. J. Phys. Chem. A 1998, 102, 1995–2001. (24) O’Boyle, N. M.; Tenderholt, A. L.; Langner, K. M. J. Comput. Chem. 2008, 29, 839–845. (25) Becke, A. D. J. Chem. Phys. 1993, 98, 5648–5652. (26) Zhao Y.; Truhlar, D. Theor. Chem. Acc. 2008, 120, 215–241. (27) Yanai, T.; Tew, D. P.; Handy, N. C. Chem. Phys. Lett. 2004, 393, 51–57.



Page 30 of 30

30 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60

Table of Contents Graphic


Helquat Dyes - ACS Publications - American Chemical Society

Recommend Documents